US5913810A - Position maintenance device for the shaft of a hydraulic cylinder - Google Patents
Position maintenance device for the shaft of a hydraulic cylinder Download PDFInfo
- Publication number
- US5913810A US5913810A US08/966,186 US96618697A US5913810A US 5913810 A US5913810 A US 5913810A US 96618697 A US96618697 A US 96618697A US 5913810 A US5913810 A US 5913810A
- Authority
- US
- United States
- Prior art keywords
- shaft
- safety valve
- valve
- maintaining
- hydraulic cylinder
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B13/00—Details of servomotor systems ; Valves for servomotor systems
- F15B13/01—Locking-valves or other detent i.e. load-holding devices
Definitions
- the present invention concerns a device for maintaining the shaft of a hydraulic cylinder in position. It is also used to detect leaks in the return circuit of the motor chamber.
- Hydraulic shafts are frequently used to propel the raising and lowering elements of a supporting structure. These devices are well known and are used in the transportation field, as well as in construction and other areas requiring frequent raising and lowering of loads that are too heavy for people to lift.
- the conventional way of maintaining the charge on a shaft is to use an anti-return valve inserted in the valve supply circuit opening in the direction of the shaft outlet chamber. Maintaining the charge in this way ensures that the device operates properly so long as the valve remains sealed. This is a quality control feature incorporated during the manufacturing process.
- the valve may either gradually or suddenly fail to seal after a certain period of time for various reasons connected to its operation, or due to aging or even a minor undetected structural defect.
- One possible cause could be a structural defect such as a ball bearing that is not perfectly spherical, or a solid impurity from the oil circuit lodging in the valve, or some other source of faulty mechanical contact or irregular thickening between the valve body and its socket.
- valve To prevent failure in a function as important as cylinder maintenance, the valve must be completely sealed.
- lifting cylinders are associated with blocking-locking mechanical devices, for example, locking pins or safety stops.
- the goal of the invention is to eliminate the need for the supplemental mechanical retention devices which have been necessary in the past to safely maintain a charged hydraulic cylinder locked in position.
- the invention proposes a device which maintains the shaft of a hydraulic cylinder, at least a single-effect cylinder, in position, comprising a chamber, which may be at the shaft outlet, and at least one anti-return valve mounted in the chamber supply circuit, opening toward the chamber, wherein the maintenance device consists of a hydraulic insulation block through which the chamber is supplied, characterized in that:
- the anti-return valve called the primary valve
- the primary valve is completed by an anti-return safety valve separated from the primary valve and mounted upstream in the chamber supply circuit, opening in the same direction toward the chamber;
- a sluice with an anti-return valve at each of its two inlets-outlets consisting of first the primary valve, which is the valve closest to said chamber, and second, the safety valve;
- This invention has multiple applications in the many situations where a load must be raised or lowered and the cylinder shaft must be maintained in a holding position, or more specifically, the extended position.
- One example would be lifting the cargo to load a vehicle transport trailer, raising and holding the platforms or supporting plates on such trailers, or the like.
- the shaft of the cylinder can be locked in any position
- the hydraulic device of the invention locks automatically without being costly
- FIG. 1 is a general schematic view in cross-section showing the maintenance device according to the invention mounted on the branches of a cylinder supply circuit;
- FIG. 2 is a longitudinal cross-section of a first embodiment of the maintenance device
- FIGS. 3 and 4 are, respectively, enlarged longitudinal cross-sections of the central portion of the maintenance device in each of two embodiments: one with a conical valve, and the other with a totally sealing valve, with the valves shown closed;
- FIG. 5 is a general schematic cross-section showing the simplified variation of the maintenance device according to the invention attached to the supply branches of a shaft with valves, which are shown closed;
- FIG. 6 is a longitudinal cross-section of the simplified variation of the maintenance device.
- the device for maintaining the position of the shaft of a hydraulic cylinder 1 is shown in the form of an insulation unit 2 mounted between one branch 3 and another branch 4 supplying power fluid through an inlet chamber 5 and an outlet chamber 6 on the shaft 7 of a hydraulic cylinder 1.
- This insulation unit 2 forms a hydraulic block 8 sealing a sluice-chamber 9, which, for the sake of convenience, will be referred to simply as a sluice.
- Said sluice has a lower opening 10 with a primary anti-return valve 11 hydraulically connected with the outlet chamber 6 of cylinder shaft 7 and opposite it, an upper opening 12 with an anti-return safety valve 13 communicating hydraulically with a hydraulic inlet 14 extending into a transverse channel 15 supplying power fluid from the outlet chamber 6 through the hydraulic inlet 14.
- the primary anti-return valves 11 and the safety valve 13 are physically distinct and moves from the top to the bottom, as in the drawings, that is, in the direction of flow from outlet chamber 6 of shaft 7 through hydraulic inlet 14.
- primary valve 11 takes the form of a ball bearing anti-return valve 16 forced to close against the seating adapted to fit it, for example, conical element 17, traversed through the center by lower opening 10.
- the return force comes from a return spring 18 enclosed in housing 19 near the lower extremity of insulation unit 2.
- the anti-return safety valve 13 in the first variation is made of a truncated piece with an active conical surface which, in closed position, contacts a circular rim 21 of an annular abutment 22 perforated through the center by upper opening 12.
- Safety valve 13 opens conventionally and automatically due to incidental pressure.
- Safety valve 13 is opened by some means outside insulation unit 2, for example, the force of the pressurized hydraulic fluid supplying the return chamber of the shaft, or some other means. It also opens primary valve 11 in succession.
- safety valve 13 extends downward into a lower control shaft 23 which has a return spring 24 on its lateral surface, in closed position.
- Said control shaft 23 terminates in a free extremity with an upright contact surface which passes through lower opening 10 of sluice 9 to abut the body of primary valve 11 and open it, that is, pushing it out of its seating 17 when it encounters the elastic return force from spring 18.
- Safety valve 13 is integral with a means which slows its closure in order to differentiate between closing this valve and closing primary valve 11. This eliminates considerable dynamic pressure, and consequently any flow into sluice 9 during the phase of closing safety valve 13.
- This feature is important because it permits one connection to be used for perfecting the seal and thus increases efficiency of the safety valve.
- This type of valve and connection is called a total seal valve 26. It is the ideal way to seal sluice 9 and reinforce maintenance of the position of the charged cylinder shaft. This variation is shown in FIG. 4 in the form of total seal valve 26 with connection 27, which may be a toric connection, resting on its groove-like seating 28.
- Another example of an embodiment of a total seal valve would be to either partially or totally surround the conical surface of the body of safety valve 13 shown in FIG. 3 with a coating or a sealing material pressing upon shoulder 22, preferably beveled for this purpose.
- One of the merits of the invention is that it offers the possibility of using a total seal valve, such as valve 26, for the second valve, called the safety valve, since there is no dynamic pressure against the seating when the valve is closed.
- the means for slowing the return course of safety valve 13, in the example shown, is an upper, composite mechanical connector 29 consisting of a movable, guided device.
- This upper composite mechanical connector 29 consists of three freely moving portions which are guided and move in relation to one another.
- Counterweight 34 on composite mechanical connection 29 comprises a seal 38 near its lower extremity, sealing this segment from chamber 32, within which piston-button 30 is displaced.
- the upper movable device consists of a final segment 39 in the form of a shaft integral with the valve body.
- Said shaft 39 has one upper cylindrical extremity toward the top, forming an end piston 40 sliding with some play along guide-groove 35 formed in supplemental piece 36.
- Said supplemental piece 36 laterally defines, along with insulation unit 2, an annular chamber 41 for passage of the oil which acts upon the body of safety valve 13.
- Piston-button 30 actuates safety valve 13 to open using a force to displace it downward originating from a control means, for example, the force originating from the pressure of the power fluid in return chamber 5 of cylinder shaft 7 exerted on the upper surface of piston-button 30 placed in the supply conduit of said return chamber.
- the force which opens safety valve 13 may originate from another means or another energy source.
- shock absorbing effect results from oil in reservoir-chamber 42 acting as a buffer, which will be progressively expelled from this reservoir-chamber 42 as safety valve 13 returns to the closed position.
- the oil will actually be driven out of this chamber as it is forced along end piston 40 by the play between the piston and its guide-groove 35.
- the shaft of the safety valve is in viscous contact with oil and provides additional shock absorption. This feature works together with the shock absorption provided by variations in rigidity between the return springs on the valves or shape variations in the hydraulic components. One or both of these parameters may be used alone or in combination.
- Sluice 9 communicates hydraulically through channel 43 with a pressure sensor or detector 44, for example a manometer inserted in the electrical or electronic circuit, producing a visual, auditory, or other type of signal if there are any leaks.
- a pressure sensor or detector 44 for example a manometer inserted in the electrical or electronic circuit, producing a visual, auditory, or other type of signal if there are any leaks.
- FIG. 2 shows mechanical block 45 of the manometer 44 and its two output pins 46 and 47 for electrical connection with the detection circuit.
- some independent means activates the safety valve, such as an electromechanical or electromagnetic means or the like.
- the maintenance device of the invention is completely reversible insofar as the supply branches are concerned. Therefore, the outlet of insulation unit 2 may be connected to inlet chamber 5, or conversely, outlet chamber 6 may be connected directly to a pressure source.
- the first operation described concerns cylinder 1 and the displacement of its shaft 7 for raising and lifting, and next, the operation of insulation unit 2 as it is used to maintain the charged position at the desired height.
- Cylinder shaft 7 extends when calibrated pressure reaches the hydraulic inlet 14 of hydraulic block 8. This pressure control will automatically open both valves 13 and 11, one after the other, as they encounter the return force of each of the springs 24 and 18, and will then supply shaft outlet chamber 6. The pressure is cut off when cylinder shaft 7 extends to the length desired.
- the cushioning effect on the safety valve then slows down the closing of the two valves, that is, it slows the closure of safety valve 13 and primary valve 11 at different rates. Relative pressure in the sluice then becomes essentially nil.
- FIGS. 5 and 6 show a simplified variation of the position maintenance device of the invention, retaining the same general functions and using the same or equivalent operating means.
- piston-button 30 does not communicate with the exterior, but with the flow of power fluid rising in shaft 7 of the hydraulic cylinder.
- the position maintenance device applies mainly, but not exclusively, to a hydraulic cylinder 1 supporting a load held by a support to be raised, lowered, and safely maintained in the desired position.
- the position maintenance device consists of a hydraulic insulation unit 2 in the form of a hydraulic block 8 mounted between two branches 3 and 4 supplying power fluid to the inlet chamber 5 and the outlet chamber 6, respectively, of shaft 7 in the case of a dual-effect cylinder.
- Hydraulic bock 8 encloses a sluice-chamber 9 comprising an lower opening 10 with a primary anti-return valve 11 connecting it to outlet chamber 6, and an upper opening 12 with an anti-return safety valve 13 communicating hydraulically with a hydraulic inlet 14 extending into transverse channel 15. Valves 11 and 13 move from top to bottom, as in the drawings.
- primary valve 11 has a ball bearing 16 elastically pushed into closed position against its seating by spring 18.
- Safety valve 13 in the embodiment of this variation shown, has a flat, circular body 48 with a raised area of smaller diameter than its housing 49.
- annular groove 50 accommodating seal 51, which may be a toric seal. It is elastically forced to close against its seating by a coaxial return spring 52 at the origin of control shaft 23, the lower extremity of which can pass through lower opening 10 to exert mechanical force against ball bearing 16.
- This safety valve 13 ensures that the charged position is maintained.
- Valve 13 ensures that the device is safely maintained in position. However, the effectiveness of this safety valve depends upon the strength of its connection after many maneuvers.
- This valve must be dependable enough to close even if there is only a very slight or hardly any flow of liquid.
- this feature slows down the closing of safety valve 13 using a delay mechanism which fragments movable upper element into a counterweight 34, sliding freely in an axial direction, the upper end of which is in contact with the base of piston-button 30 displaceable along chamber 32, which is open to the atmosphere.
- counterweight 34 is opposite the extremity of a piston 40 connected to the body of the valve through a reservoir-chamber 42 full of oil used for shock absorption.
- the delay feature which closes the valves at different times can be obtained using different methods alone or in combination, for example: varying the rigidity of the return springs on the valves; the viscous contact of the shaft of valve 13 in sluice-chamber 9; and, generally speaking, using oil to slow the shaft, and the shape and dimension of the hydraulic components.
- Transverse channel 15 of the hydraulic inlet 14 has a shunt 53 leading into a buffer-chamber 54 beneath piston-button 30. For this reason, buffer-chamber 54 no longer communicates with the exterior through a vent. It is connected to inlet 14 and filled with pressurized oil. As a result, the risk of corrosion due to exposure to the elements is completely eliminated.
- Another advantage of this variation concerns sealing. Sealing is less important, since leaks flow into the line of the hydraulic circuit. Consequently, it is possible to eliminate the seal between buffer-chamber 54 and the inlet of conduit 3 in the upper portion of piston-button 30, on the one hand, as well as the seal between the and piston 40 of safety valve 13 and buffer-chamber 54, on the other hand.
- This pressure is sufficient to open first, safety valve 13, and then primary anti-return valve 11, supplying the shaft through outlet chamber 6 on shaft 7.
- Shaft 7 rises with the load it supports to the desired level, which may or may not have been pre-programmed. Pressure is then cut off and the shaft is immobilized in position. Immediately after it is immobilized, the charge causes the oil to flow back for a short time.
- Safety valve 13 closes a second time within sluice-chamber 9, as there is no pressure because primary valve 11 has previously closed and insulated it from pressure.
- the closure of the valve in the absence of dynamic pressure and liquid flow controls the safety valve seal and prevents the valve from leaving its housing.
- valve closings various means already described above are used, such as: variations in the rigidity of the valve return springs; viscous contact of the shaft of valve 13 in sluice-chamber 9; and generally speaking, slowing down the course of the shaft in the oil, as well as the shape and dimension of the hydraulic components.
- Two anti-return valves ensure that the device is maintained in charged position.
- Primary valve 11 with bearing 16 closes to immediately maintain the charge.
- Safety valve 13 ensures position maintenance.
- the safety valve Since it is made with a seal 51 which is not subjected to enough force during closure to affect its hold, the safety valve provides a highly reliable seal.
- the load will remain in position almost indefinitely.
- Controlling the descent of shaft 7 of the charged cylinder requires that both valves be opened.
- the source of the force opening them is controlling pressure. This may consist of the pressure exerted on the other chamber of the dual-effect cylinder, or pressure independent of the control means.
- piston-button 30 which is displaced and causes displacement of the valve body when piston-button 30 contacts the end of the upper extension 40 of the shaft of safety valve 13, and by mechanical translation.
- the shaft of the safety valve continues to descend.
- the lower extremity of its shaft 23 abuts and pushes upon the stopper of the primary valve, and as it follows it course, causes it to open.
- valves are no longer kept open and, in the same manner as described above, safety valve 13 is closed more slowly than primary valve 11.
- the movable element unit and piston-button 30 move upward.
- one object of this invention is for the safety valve to close if there is even a slight flow of oil, in order to avoid damaging or dislodging the valve seal and to ensure that the device operates reliably.
- the shaft can also be driven back by the force of gravity coming from the loaded platform.
- the device of the invention can be oriented to move in the opposite direction from that shown in the drawings, or any other orientation.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR9613778 | 1996-11-07 | ||
FR9613778A FR2755481B1 (fr) | 1996-11-07 | 1996-11-07 | Dispositif de maintien en position et sous charge d'un verin hydraulique |
Publications (1)
Publication Number | Publication Date |
---|---|
US5913810A true US5913810A (en) | 1999-06-22 |
Family
ID=9497542
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US08/966,186 Expired - Lifetime US5913810A (en) | 1996-11-07 | 1997-11-07 | Position maintenance device for the shaft of a hydraulic cylinder |
Country Status (11)
Country | Link |
---|---|
US (1) | US5913810A (de) |
EP (1) | EP0935715B1 (de) |
CN (1) | CN1103411C (de) |
AT (1) | ATE258274T1 (de) |
CA (1) | CA2270579A1 (de) |
DE (1) | DE69727307T2 (de) |
ES (1) | ES2216132T3 (de) |
FR (1) | FR2755481B1 (de) |
RU (1) | RU2191298C2 (de) |
UA (1) | UA46875C2 (de) |
WO (1) | WO1998020260A2 (de) |
Cited By (16)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20040113474A1 (en) * | 2002-06-28 | 2004-06-17 | Stephen Lambrecht | Vehicle seat adjuster |
EP1741936A1 (de) * | 2005-07-08 | 2007-01-10 | THOMAS MAGNETE GmbH | Fördermengenregelventil für liquide Medien |
US20070157971A1 (en) * | 2004-07-12 | 2007-07-12 | Tiefenbach Control Systems Gmbh | Releasable non-return valve |
US20070209502A1 (en) * | 2006-03-10 | 2007-09-13 | Luigi Pasquali | Dual-effect hydraulic actuator handling system for gate moving |
US20080143176A1 (en) * | 2006-12-15 | 2008-06-19 | Wei-Teh Hsu | Anti-Reverse Safety Device for Hydraulic Cylinder of Wheeled Vehicle |
US7678132B2 (en) | 2001-09-06 | 2010-03-16 | Ovalis, Inc. | Systems and methods for treating septal defects |
US7740640B2 (en) | 2001-09-06 | 2010-06-22 | Ovalis, Inc. | Clip apparatus for closing septal defects and methods of use |
US7846179B2 (en) | 2005-09-01 | 2010-12-07 | Ovalis, Inc. | Suture-based systems and methods for treating septal defects |
US8070826B2 (en) | 2001-09-07 | 2011-12-06 | Ovalis, Inc. | Needle apparatus for closing septal defects and methods for using such apparatus |
US8579936B2 (en) | 2005-07-05 | 2013-11-12 | ProMed, Inc. | Centering of delivery devices with respect to a septal defect |
CN104019080A (zh) * | 2014-06-23 | 2014-09-03 | 柳州柳工液压件有限公司 | 补油油缸 |
CN104105890A (zh) * | 2012-02-16 | 2014-10-15 | 克斯美库股份有限公司 | 带助力机构的缸装置 |
US20190032680A1 (en) * | 2016-03-31 | 2019-01-31 | Lohr Industrie | Dual-Valve Security Unit for Hydraulic Cylinders |
WO2019030354A1 (en) * | 2017-08-11 | 2019-02-14 | Eaton Intelligent Power Limited | COLLECTOR HAVING A LOADED PILOT STOP VALVE AND A PURGE VALVE |
US11415242B2 (en) * | 2018-11-27 | 2022-08-16 | Hamilton Sundstrand Corporation | Servo valve |
US11618232B2 (en) | 2017-08-01 | 2023-04-04 | Moog Gmbh | Apparatus for controlling the switch-over of hydraulic cylinders |
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---|---|---|---|---|
US6935409B1 (en) | 1998-06-08 | 2005-08-30 | Thermotek, Inc. | Cooling apparatus having low profile extrusion |
MXPA02000862A (es) | 2000-06-01 | 2003-07-14 | Bristol Myers Squibb Pharma Co | Lactamas substituidas por succinatos ciclicos como inhibidores de la produccion de proteina abeta. |
US9113577B2 (en) | 2001-11-27 | 2015-08-18 | Thermotek, Inc. | Method and system for automotive battery cooling |
US8262058B2 (en) * | 2008-08-28 | 2012-09-11 | Kot Norbert J | Balanced pilot operated check valve |
US9611871B2 (en) | 2013-09-13 | 2017-04-04 | Norbert J. Kot | Pneumatic valve assembly and method |
DE102019218400A1 (de) * | 2019-11-27 | 2021-05-27 | Hawe Hydraulik Se | Ventilkegel, Lasthalteventil mit Ventilkegel und Verfahren zur Montage eines Rückschlagventils |
FR3104653B1 (fr) | 2019-12-17 | 2021-11-19 | Lohr Ind | Bloc de securite a electrovanne pour verin et circuit hydraulique contenant plusieurs verins equipes de tels blocs |
DE102020109615A1 (de) | 2020-04-07 | 2021-10-07 | Neumeister Hydraulik Gmbh | Vorrichtung zum halten eines schafts eines hydraulikzylinders in stellung und verfahren zum entsperren und absperren eines sekundär-rückschlagventils der vorrichtung |
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1996
- 1996-11-07 FR FR9613778A patent/FR2755481B1/fr not_active Expired - Fee Related
-
1997
- 1997-11-06 CN CN97199511A patent/CN1103411C/zh not_active Expired - Lifetime
- 1997-11-06 ES ES97913266T patent/ES2216132T3/es not_active Expired - Lifetime
- 1997-11-06 CA CA002270579A patent/CA2270579A1/fr not_active Abandoned
- 1997-11-06 RU RU99112128/06A patent/RU2191298C2/ru active
- 1997-11-06 DE DE1997627307 patent/DE69727307T2/de not_active Expired - Lifetime
- 1997-11-06 UA UA99063105A patent/UA46875C2/uk unknown
- 1997-11-06 AT AT97913266T patent/ATE258274T1/de not_active IP Right Cessation
- 1997-11-06 EP EP97913266A patent/EP0935715B1/de not_active Expired - Lifetime
- 1997-11-06 WO PCT/FR1997/001994 patent/WO1998020260A2/fr active IP Right Grant
- 1997-11-07 US US08/966,186 patent/US5913810A/en not_active Expired - Lifetime
Patent Citations (10)
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FR2216468A1 (de) * | 1973-02-07 | 1974-08-30 | Danfoss As | |
US4355565A (en) * | 1980-03-24 | 1982-10-26 | Caterpillar Tractor Co. | Fluid circuit with zero leak load check and by-pass valve |
GB2205385A (en) * | 1987-05-15 | 1988-12-07 | Oil Control Spa | Improvements in a load holding and control valve, in particular for hydraulic circuits with either open or closed centre directional control valve |
US4913190A (en) * | 1989-04-24 | 1990-04-03 | Deere & Company | Detent mechanism for a control valve |
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EP0736443A1 (de) * | 1995-04-04 | 1996-10-09 | Applied Power Inc. | Hydraulikanlage zum Kippen einer Fahrerkabine |
Cited By (23)
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---|---|---|---|---|
US8758401B2 (en) | 2001-09-06 | 2014-06-24 | ProMed, Inc. | Systems and methods for treating septal defects |
US7678132B2 (en) | 2001-09-06 | 2010-03-16 | Ovalis, Inc. | Systems and methods for treating septal defects |
US7686828B2 (en) | 2001-09-06 | 2010-03-30 | Ovalis, Inc. | Systems and methods for treating septal defects |
US7740640B2 (en) | 2001-09-06 | 2010-06-22 | Ovalis, Inc. | Clip apparatus for closing septal defects and methods of use |
US8747483B2 (en) | 2001-09-07 | 2014-06-10 | ProMed, Inc. | Needle apparatus for closing septal defects and methods for using such apparatus |
US8070826B2 (en) | 2001-09-07 | 2011-12-06 | Ovalis, Inc. | Needle apparatus for closing septal defects and methods for using such apparatus |
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US8579936B2 (en) | 2005-07-05 | 2013-11-12 | ProMed, Inc. | Centering of delivery devices with respect to a septal defect |
EP1741936A1 (de) * | 2005-07-08 | 2007-01-10 | THOMAS MAGNETE GmbH | Fördermengenregelventil für liquide Medien |
US7846179B2 (en) | 2005-09-01 | 2010-12-07 | Ovalis, Inc. | Suture-based systems and methods for treating septal defects |
US20070209502A1 (en) * | 2006-03-10 | 2007-09-13 | Luigi Pasquali | Dual-effect hydraulic actuator handling system for gate moving |
US20080143176A1 (en) * | 2006-12-15 | 2008-06-19 | Wei-Teh Hsu | Anti-Reverse Safety Device for Hydraulic Cylinder of Wheeled Vehicle |
CN104105890A (zh) * | 2012-02-16 | 2014-10-15 | 克斯美库股份有限公司 | 带助力机构的缸装置 |
CN104105890B (zh) * | 2012-02-16 | 2016-02-24 | 克斯美库股份有限公司 | 带助力机构的缸装置 |
CN104019080A (zh) * | 2014-06-23 | 2014-09-03 | 柳州柳工液压件有限公司 | 补油油缸 |
US20190032680A1 (en) * | 2016-03-31 | 2019-01-31 | Lohr Industrie | Dual-Valve Security Unit for Hydraulic Cylinders |
US10760595B2 (en) * | 2016-03-31 | 2020-09-01 | Lohr Industrie | Dual-valve security unit for hydraulic cylinders |
US11618232B2 (en) | 2017-08-01 | 2023-04-04 | Moog Gmbh | Apparatus for controlling the switch-over of hydraulic cylinders |
WO2019030354A1 (en) * | 2017-08-11 | 2019-02-14 | Eaton Intelligent Power Limited | COLLECTOR HAVING A LOADED PILOT STOP VALVE AND A PURGE VALVE |
US11415242B2 (en) * | 2018-11-27 | 2022-08-16 | Hamilton Sundstrand Corporation | Servo valve |
Also Published As
Publication number | Publication date |
---|---|
DE69727307T2 (de) | 2004-11-18 |
WO1998020260A3 (fr) | 2002-10-03 |
RU2191298C2 (ru) | 2002-10-20 |
FR2755481B1 (fr) | 1998-12-24 |
EP0935715B1 (de) | 2004-01-21 |
CA2270579A1 (fr) | 1998-05-14 |
ES2216132T3 (es) | 2004-10-16 |
UA46875C2 (uk) | 2002-06-17 |
CN1103411C (zh) | 2003-03-19 |
EP0935715A1 (de) | 1999-08-18 |
FR2755481A1 (fr) | 1998-05-07 |
WO1998020260A2 (fr) | 1998-05-14 |
DE69727307D1 (de) | 2004-02-26 |
CN1244236A (zh) | 2000-02-09 |
ATE258274T1 (de) | 2004-02-15 |
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